Method of forming fluffed filamentary masses and article produced thereby



July 7, 1953 T. R. slMKlNs ErAL 2,544,780

METHOD OF FORMING FLUFFED FILAMENTARY MAssEs AND ARTICLE PRODUCEDTHDRDDY 2 Sheets-Sheet l Filed Jan. 11. 1949 IN VEN TORS Hamas SIM/a.;By iclzard M .faswr July 7, 1953 T. R. slMKlNs ErAL METHOD DE EDRMINGELUEEED EILAMENTARY lMssEs AND ARTICLE PRODUCED TEEEEEE4 Filed Jan. 1l.1949 -2 Sheets-Sheet 2 DENN Patented July 7, 19x53 METHOD oF ronMINGemmen Y. TARY MAssEszAND Annone .PRODUCED THEREBY 'Thomas' R.'SimkinsfEast Williston, and Richard` N. Jaspergfaldwin, N. Y.,assignorsyby mesne assignments, -to- John's-Manville Corporation, NewYork, NJ Y., fa corporation ,of New York vvApplication January 11,1949,.;SerialNo. .70,316 j 8 r(Ella/ilus. (Cl. 1`54-92) This applicationvrelates to the preparation o a mass of glass iibers or laments in whichmany or most of the fibers are given a suiflcien't twist or Wave-likecurl so that'ethe entire mass has an open fluffy appearance(thoughratherV stili and resilient to the touch) as distinguished froman ordinary glass mat where the fibers A'are held together Vin closecontact.' "Such a mass of fibers has many uses of which the mostimportant now appears to: be its use as an air iilter medium in airconditioning systemsy and the'li'ke'.

This `application is based upon ourdisc'overy that the fibers can .begiven this curling effect if they .are laid down cna rapidly rotatingdrum in a series of layers, with'e'ach 'layer made'up of a number of.strata'bfparallel bers 'but with the bers in the different layers,crossing each other at a very slightangle, and if' steps .are taken toincrease thesurface 'tensionor adhesion between the parallel fibers` inea'ch'layerso that these parallel bers will tend to'res'ist separationas the mat is expanded'.v

When this Vis done, and the fiber massris cut from the drum .andexpanded, v`the ,parallel'flbers within each layer are pulled apart'throughout portions of their lengthbutthe resistance of this I pullingor separating apparently 'causes the bers to bendJ buckle and wave sothat the mass is relatively open and fluffy in appearance. 'In somecases the surface layers will bey flatter than the inside layers,particularly the bottom'layer which ordinarily rests on Ja flatj'surface while 4being formed. Y e

Almost any type of bindercan .be-.used toincrease the adhesionbetweenthe parallel Yfibers in a given'layelp In fact, `simply addingmoisture will "give this 'effect toa limited extent.' How--y ever, weprefer to use 'a'l more permanent binder and preferably this binder issprayed or otherwise applied on the roller or 'drum'on which l'thelayers of fiber are v4accumulated; This treatment has the advantage'that it is easy 'to control the amount of binder applied andthis'fcanibekept quite uniform through the entire mass.

The binder employed may be .any of the binders commonly used with glassfibers and maybe of either the soluble or insoluble type. For examplethev solublev bindersl aresuch materials" as starch or glue. Ordinarily,we y'prefer to use a binder which can locklthe fibers lin, Aplacesuchas a thermosetting resin. Inthis vcategoryffare the phenolic resins,synthetic` latex; ,ureafjand melamine resinsl `and .the like."Thermoplastic resins such asfstyrene orpolyvinyl 4compounds may also beemployed In laying `the fibers down on the drum vthe best method ofoperating is to draw out a large number of parallel Yiibers from a.single furnace, For example, .about 100 parallel `fibers may be drawnout from the furnace in a form somewhat like a band with a distance offrom 12 kto 14 inches between the outsidebers. This furnace is caused tomove .slowlyv across .the face of the drum as the drum rotates rapidlysothat a large number of rotations of the drum will have occurred beforethekber on the back edge of the band from 'the furnace movesvup to thepoint where the first fiber from the furnace was applied to'the drumwhen the operation started. For example, if 'theffurnace is 14 incheslong and advances only vabout \1/4inch foreach rotation of the drum,then at any givenl point onxthe drum over which the entire furnacepasses, there will be about 56 separate strata of glass fibers laid downall of which are parallel. 'On the return movement ,y another '56 strataofbers will be laid downfto make another separate layer of parallelfibers. Ordinarily the drum on which the fibers are collected is quitelarge, say, about 12 feet in circumference and it may rotate 'at a speedof about .20'0 revolutions per minute. With a drum of this proportionand this speed a 14-inch furnace can be operated on a traverse ranginganywhere from. 111e-inch per revolution up to 3 inches per revolution.We have found in general that itv isfbest to operate with a furnacemoving somewhere between 1A to `'2l/2 inches for each .revolution of thedrum. The ynumber of layers of glass is not critical though in generalit should `exceed twenty-five. Ordinarily the number `will befverymuch..greater .as economy demands that a relatively thick mass be builtup on the drum, kand usually a relatively thick final sheet isy desired.It ki-s apparent that the condensed mat v.formed by the operationdescribed above iscomposed of a plurality .of layers `of Alilaments withthe laments extending lin the `same general direction across the mat butwith filaments of adjacent layers crossing atacute angles.

.centrifugal vforce.i` In some cases as Alittle as 2% of binder may besuflicient, but if more is desired, additional quantities of binder canbe applied later as described below.

In place of applying the binder as the glass is accumulated on the drum,we find that the entire mat still in condensed form canV be immersed inbinder and any excess blown or drawn off, or the mat may be partlyexpanded, then immersed in or sprayed with binder with the excess suckedoff and the expansion continued. In any of these cases at least part ofthe expansion takes place after the binder is addedto increase theadhesion between the fiber bundles.

When the fiber is cut from the drum and expanded in a directiongenerally transversely of the lay of the fibers, it will be found thatthe curling tendency starts almost as soon as the layers of parallelfibers start to open up, but the best effects are had when the mat isgiven a relatively large expansion, say to a length in excess of twentytimes its original length and preferably as much as fifty times itsoriginal length. For example a good expansion is one 'where' a mathaving an initial length of 6 feet in the `direction of expansion isexpanded to a total length of from 300 to 540 feet. If too muchexpansion is applied, the total area willnot be materially increased butthe mat will tend to narrow to compensate for increased length. Ingeneral, it will be found that the area of the initial mat cannot beexpanded much more than 30 times its original area.

When the mass has been expanded, it will be noted that the glass appearstoV form a series of superimposed wavy layers which give the desiredresiliency but are sufficiently entangled to hold the mass together. Infact, the mat can, if desired, be split rather uniformly between itsfaces by stripping off separate layers. We believe that this structureresults from the fact that the fibers are laid down in layers with eachlayer made up of many strata of parallel fibers and that the peculiarcurly effect is largely the result'of expansion and relative movement ofthe parallel fibers within each layer.

As stated, we prefer to apply binder to the fibers while they are beingvlaid down on the drum, as this gives a uniformityof application.Ordinarily, however', it will be found that it is not feasible to applysufficient binder in this way to give the finished mat its desiredcharacteristics. In such case it ordinarily will be found desirable toincrease the stiffness of the mat by adding additional binder afterexpansion has taken place and before the final drying operation. Thiscan be done by any of the methods ordinarily used for applying binder toexpanded kglass mats, as by spraying onv the binder -or by immersing themat in solution or suspension-in the binder and removing excess binderin any desired manner. A good final product for use in air filters mayhave anywhere from 8% to 60% by weight of binder (based on the weight ofthe glass) included in it. The principal thing is to have enough binderto lock the fibers together where they cross and Contact each other. Ifthis additional binder is applied by spraying vafter expansion it tendsto increase the concentration on the top surface, which 'stiffens thissurface against collapse. The bottom surface which rests on a stationaryor moving support naturally tends to be flat.

After the mat has been expanded it is taken through a drier to drive offany excess moisture and if a thermosetting resin 'has been used, it canbe cured or set at this time. It is understood 4 that the resin used inliquid form either for spraying on the mat or for immersing the mat isan unset resin.

Some idea of the density of our mat can be had from the fact that a matprepared for use as an ordinary air filter will be so light and openthat it may weigh only from 11/2'to 8 ounces per cubic foot.

Our invention may be understood from the following example, referencebeing had to the accompanying. drawings in which Fig. 1 is a plan viewof a mat made in accordance with our invention; Fig. 2 is a side view ofthis mat with a group of layers separated; Fig. 3 is a perspective viewof the mat; Fig. 4 is a section through a drum on which the glass fibersare wound; Fig, 5 is a face view of this drum; Fig. 6 is a plan view ofan expander for expanding the mat wound on the drum and Fig. '7 is aside view of such expander.

Referring to Figs. 4, 5, 6 and '7, the glass was accumulated on a drumI0 four feet in diameter and six feet long rotating at a speed of 200revolutions per minute. A furnace I2 with 100 glass fibers (as indicatedat I4) running from it traversed the face of the drum I0 at a speed suchthat it advanced 11/2 inches for each revolution of the drum. In thedrawings this movement is greatly exaggerated to indicate the nature ofthe movement. Actually the glass fibers on the drum were substantiallyparallel as indicated by the figures stated above. The formation ofglass on the drum I0 was maintained until the mat I6 on the drum weighedabout vpounds and during all-this time spray nozzles I8 were movedslowly back and forth across the face of the drum spraying on theaccumulated glass a light spray of a standard form of liquid phenolicresin (a resin which was maintained in a water-soluble state and keptrelatively fluid with the water present). After sufficient fiber hadaccumulated on drum I0, mat I6 was cut across the face of the drum andlaid out flat to form a mat measuring approximately 6 feet across thefibers by 12 feet in the direction of the fibers. An unexpanded portionof this mat is indicated at 20 in Figs. 6 and 7. This mat was thenexpanded along a line running approximately at right angles to thefibers as indicated in Figs. 6 and 7 to give a mat approximately 450feet long. A space of from 10 to 15 feet was provided between the pointof pull on the fibers as indicated at .22 and the unexpanded portion 20,so that the mat could expand progressively. A moving screen 24 supportedthe fibers at this time and during this expansion additional binder wassprayed on the top surface as .indicated at 26 inlan amount sufficientso that the final weight of binder was between 40% and 60% of the weightof the glass. The expanded mat was then taken up by conveyor 28 to adrier 30 where it was dried at a temperature of about 300 F. and cutinto separate pieces of desired size.

The resulting product was a resilient, open mass of stiffened glassfiber having a weight of between 11/2 and 8 ounces per cubic footadapted for use in air filters and the like consisting of a plurality ofsuperimposed layers of waved, entangled but non-compacted glass fiberswith the fibers of the various layers sufficiently entangled with eachother to hold the mass together. This mass contained plastic binderamounting to between 30% and 60% of the weight of the glass which servedto lock` the fibers together at their intersection and stiften them togive resilience to the mass. In cases Where the binder was applied onlyas the glass fibers were first being accumulated on the drum the amountof fiber ranged down to 8% of the Weight of the glass. The fibers in theproduct Were relatively long, that is, a major proportion of them wouldrun from one edge of the cut piece to another edge either adjacent oropposite and only a minor proportion (as where bers had been broken)would show ends Within the mass.

In Figs. 1 to 3 we have endeavored to illustrate a mat made inaccordance with our invention in the accompanying drawing but have foundthe article exceedingly difficult to depict since the details of theconstruction are represented by myriads of tiny fibers which cannot beshown separately. However, we have endeavored in the drawing to givesome indication of the nature of the product.

The representation in Fig. 2 is more or less dlagrammatical, as in factthe layers do not separate quite as clearly as indicated in thatdrawing, as the entanglement between the layers is caused by the veryfine fibers which are hard to illustrate.

It is understood that the examples given are intended to be illustrativeonly and not to limit the nature of our invention.

What we claim is:

1. The method comprising forming a mat of a plurality of layers offilaments, with the filaments extending generally transversely of themat and with the filaments of adjacent layers crossing at acute angles,drawing the mat in a direction at right angles to the general lay of thefilaments to expand the mat, applying a minor proportion of an unsetbinder to the mat between the time that the mat is partly formed and thetime when it has been partly expanded, continuing the drawing of the matwet with such binder on it until the layers of the mat assume acorrugated or undulatory form, applying additional unset binder to themat and setting the binder.

2. A product comprising a plurality of superposed layers of glassfilaments, with the filaments of adjacent layers in crossingrelationship, the layers lying substantially parallel to one another andeach layer being approximately uniform, contiguous undulationsprojecting above and below the median plane of the layer and extendofadjacent layers crossing at slight angles, expanding the mat in adirection transversely of the general lay of the filaments in thecondensed mat until an openfiuify mass of waved filaments is formed,applying an unset binder to the open fiuffy mass and setting the binder.

4. A method comprising forming a condensed mat of a plurality oflayersof filaments with the filaments of all layers extending in thesame general direction across the mat but with filaments of adjacentlayers 'crossing at slight angles, expanding the mat in a directiontransversely of the general lay of the filaments in the condensed matuntil an open iiuffy mass of waved filaments is formed, applying anunset binder to the mat during expansion thereof, and setting the binderafter expansion is completed.

5. A method comprising forming a condensed mat of a plurality of layersof filaments with the filaments of all vlayers eiltending in the samegeneral direction across the mat but with filaments of adjacent layerscrossing at slight angles, applying a liquid to the filaments of thecondensed Y mat, expanding the` mat in a direction transversely of thegeneral lay of the filaments in the condensed mat until an open fluffymass of waved filaments is formed, applying an unset binder to the openfluffy mass and setting the binder.

6. A method comprising forming a condensed v mat of a plurality oflayers of filaments with the filaments of all layers extending in thesame gening at an angle to the filament directions, superposed layersbeing tied together by a multiplicity of interconnecting filaments, abinder bonding said filaments into a substantially unitary body, withthe concentration of binder being greater at the top of such productthan at the bottom whereby the top surface of the structure is stiffenedagainst collapse.

3. A method comprising forming a condensed mat of a plurality of layersof filaments with the filaments of all layers extending in the samegeneral direction across the mat but with filaments eral directionacross the mat but with filaments of adjacent layers crossing at slightangles, applying a liquid to the filaments of the condensedmat,'expanding the mat in a direction transversely of the general lay ofthe filaments in the condensed mat until an open fluffy mass of wavedfilaments is formed, applying an unset binder to the mat duringexpansion thereof, and setting the binder after expansion is completed.

7. The method specified in claim 5 wherein said liquid comprises anunset binder.

8. The method specified in claim 6k wherein said liquid comprises anunset binder.

THOMAS R. SIMKINS.

RICHARD N. JASPER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,081,060 Modigliani May 18, 1931 2,131,024 Cordts Sept. 27,1938 2,234,986 Slayter et al. Mar. 18, 1941 2,298,295 Hyatt et al. Oct.13, 1942 2,410,744 Powers Nov, 5, 1946 2,428,654 Collins Oct. 7, 19472,437,799 Yorke Mar. 16, 1948 2,486,217 Slack et al. Oct. 25, 19492,505,045 Holcomb Apr. 25, 1950 2,546,230 Modigliani Mar. 27, 1951

1. THE METHOD COMPRISING FORMING A MAT OF A PLURALITY OF LAYERS OFFILAMENTS, WITH THE FILAMENTS EXTENDING GENERALLY TRANSVERSELY OF THEMAT AND WITH THE FILAMENTS OF ADJACENT LAYERS CROSSING AT ACUTE ANGLES,DRAWING THE MAT IN A DIRECTION AT RIGHT ANGLES TO THE GENERAL LAY OF THEFILAMENTS TO EXPAND THE MAT, APPLYING A MINOR PROPORTION OF AN UNSETBINDER TO THE MAT BETWEEN THE TIME THAT THE MAT IS PARTLY FORMED AND THETIME WHEN IT HAS BEEN PARTLY EXPANDED, CONTINUING THE DRAWING THE MATWET WITH SUCH BINDER ON IT UNTIL THE LAYERS OF THE MAT ASSUME ACORRUGATED OR UNDULATORY FROM, APPLYING ADDITIONAL UNSET BINDER TO THEMAT AND SETTING THE BINDER.
 2. A PRODUCT COMPRISING A PLURALITY OFSUPERPOSED LAYERS OF GLASS FILAMENTS, WITH THE FILAMENTS OF ADJACENTLAYERS IN CROSSING RELATIONSHIP, THE LAYERS LYING SUBSTANTIALLY PARALLELTO ONE ANOTHER AND EACH LAYER BEING APPROXIMATELY UNIFORM, CONTIGUOUSUNDULATIONS PROJECTING ABOVE AND BELOW THE MEDIAN PLANE OF THE LAYER ANDEXTENDING AT AN ANGLE TO THE FILAMENT DIRECTIONS, SUPERPOSED LAYERSBEING TIED TOGETHER BY A MULTIPLICITY OF INTERCONNECTING FILAMENTS, ABINDER BONDING SAID FILAMENTS INTO A SUBSTANTIALLY UNITARY BODY, WITHTHE CONCENTRATION OF BINDER BEING GREATER AT THE TOP OF SUCH PRODUCTTHAN AT THE BOTTOM WHEREBY THE TOP SURFACE OF THE STRUCTURE IS STIFFENEDAGAINST COLLAPSE.